Determining an /e/ device's fitness for network

Using /e/OS Setup
1

I think @Taurus and @egx470 are probably the SMEs on this matter, but if anyone else knows something please chime in.
When the three of us were initially experimenting with /e/ on the T-Mobile network (and it’s MVNOs) we discovered that the store-supplied S9’s weren’t up to the task, and that really only two phones were, the OnePlus 6T and the Moto G7 Plus. Now I’ve got no issue with either of these phones, but I do believe in preparedness. If one were to break or there were to be some other issue, I’d need a new device and I would say right now the leading contender is the Moto Edge 5G.
I don’t want to have another situation where my phone only works some of the time, so I’m wondering how to go about confirming that this device works with all facets of the T-Mobile network. Any ideas?

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

2

For clarification, I’ve never owned the Samsung myself. I use the Sony XZ1 Compact and have no problem getting VoLTE (or even VoWiFi) on T-mobile MVNOs.

To my knowledge, Samsung is the main OEM to avoid for custom ROMs, just due to its proprietary IMS implementation (I think I’ve got that right). And of course, the North American Samsung variants in general are a no-go.

In theory, any phone (other than a Samsung) that normally has VoLTE on the carrier, and which has an /e/ build, should still get VoLTE on that carrier after /e/ is installed.

Maybe some developer will eventually figure out how to get the Samsungs working, too.